Traffic signaling system



April z, 1940.

R. A. MccANN 2,195,892

TRAFFIC SIGNALIIG SYSTEM Filed March 1 19:59

Patented Apr. 2, A1940 TRAFFIC SIGNALIN G SYSTEM l Ronald A. McCann, Swissvale, Pa., assignor to riihe Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Appiication March 1, 1939, Serial No. 259,203

, y 6 Claims.

My invention relates to traffic signaling systems, and particularly to traflic signaling systems for controlling the movements of two or more classes of traiiic, the movement of one class vof which is given preference at all times.

A feature of my inventionis the provision of novel and improved means for controllingA two or more classes of trafc which operate over in'- tersecting trailic routes, wherein one class of trafcis givenpreference over other classes, and wherein when the preferred class is given the right-of-way to proceed, the other classes are controlled to prevent all tralic movements interfering with the movement of such preierredclass.

Apparatus embodying my invention is particularly well. adapted for controlling highway traflic onone traic route turning ontov another 'traflc route and crossing a railway track intersecting the other trafc route.

Other features and advantages of my invention will appear as the specication progresses.

I5 shall describe vone form of apparatus embodying my invention, and shall then point out the novelfeatures thereof in claims. I

`The accompanying4 drawing vis a diagrammatic view of a preferred form of apparatus embodyin my invention when applied to a traic signaling system controlling the intersection of two highway traffic routes, one route of which is paralleled bya stretch of railway track which `intersects the other traflic route at grade at the intersection of the traflic routes.

Referring to thedrawing, the reference character Al designates one traffic route, and the reference character B designates another traic route, which routes intersect each other at grade. A stretch of railway track, designated by the reference character C, as shown parallels route B and intersects route A at grade. Although track C is shown contained within route B, it is to be understood that I do not conne myself to an intersection as shown, but that the scope of my invention 4embraces any signaling system for an intersection of two interferingv traiic routes wherein trafc on one route is permitted to cross an intersecting route but is `prevented at times yfrom turning onto such intersecting, route and lacross another trafc route intersecting such intersecting traffic route. l

To aid in the understanding of my invention, I shall consider route A as being a north and south road with northbound traic moving from 4the bottom to the top of the drawing and southbound traic moving from the top to the bottom. Route B 1 shall speak of as an least andv west highway traffic.

road with eastbound trafc moving from the left to the right of the drawing and westbound traino moving from the right to the left. The railway C I shall consider as a single track railway over which trains move in both eastbound and westbound directions.

Trafiic at the intersection of routes A, B and C is governed by four right-of-way signals,` one located at each corner and designated by the reference characters D, E, F and H, and by two turnout signals LTI and LTZ. Signal D governs southbound traic moving on route A, signal E governs northbound traffic moving on route A,

signal F governs westbound traic moving on route B, While signal H governs eastbound trafc moving on route B. Signals F and H, as will appear more clearly hereinafter, are at times controlled by the operation of trains operating on track C, and in turn may serve to control the operation of such trains by indicating that the signaling apparatus is properly conditioned for a train movement across the highway intersection. To more readily distinguish signals F and H from signals D and E, I shall refer to the first pair of signals as4 being railway-highway right-of-way signals since they may control either or both railway and highway traffic, and the. latter pair of signals I shall refer to as being highway right-of-way signals since they control only While signals D, E, .F and H may take diierent forms, a preferred form is that wherein each signal comprises three distinctively colored lights, preferably a green, a yellow and a red light, designated respectively by the reference characters G, Y and R. In accordance with the usual practice, the lamps for each pair of signals D, E' and F, H are adapted to be lighted so that the signals alternately indicate proceed to one tralic route while indicating stop to the other intersecting route, and then indicate proceed to the other traine route while indicating' stop to the one` traino route. The signals are usually further controlled to display each a yellow or caution signal intermediate each displayof the proceed and stop indications for indicating that a change is being effected in the right-of-way indication for each traic route. display of the proceed and caution and stop in- `dications for each right-of-way signal is con- D trolled by a signal timer ST.

As will be presently explained, the

The twor turnout signals LTI and LT2 are lof track C. Signals LTi and LTE may take different forms and as here shown each comprises two dilerently colored directional signals each in the form of an arrow with the head pointed in the direction of the traffic moves which the signal is adapted to control. Preferably, the turnout signals are located on the signal mast of the associated railway-highway signals below the latter signals, and are provided each with a green directional arrow LP and a red directional arrow LS. As will be explained presently, the turnout signals are normally controlled oy the signal timer ST in step or register with their associated railway-highway signals, that is to say, the green directional arrow LP is illuminated when the green proceed indication G is displayed cy its associated railway-highway signal, and the red directional arrow LS is displayed when its associated 1ailwa.'iiighway signal displays its red or stop indication R, but at times the turnout signals are controlled out of register with the associated railway-highway signals so that the turnout signals display the red directional arrows LS when the associated railwayhiglnvay signals display the green or proceed indications G.

The signal timer mea-ns ST, previously referred to, may take any one of many suitable forms, and as here shown comprises three drums u* cams E, G and 'l which are secured to a shaft B and which rotate in response to the actuation of a notor M connected with the shaft 8 by a suitable train of gears indicated on the drawing by a dash line. Each of the cams 5, 5 and l is provided with a high or contact making surface and with a low or Contact breaking surface. Cam 5 is adapted to engage with its Contact making surface a contact member 9 to close a circuit controlling contact s-iil once for each complete rotation of the shaft 3, cam 5 is adapted to engage with its Contact making surface a contact member i E to close a circuit controlling contact lil-l, the contact ll2 being closed two times in each complete revolution of the shaft 8, and cani l is adapted to engage with its contact making surface a contacu member i3 to close a cixcuiiJ controlling contact lil-lll once for each complete revolution of the shaft 3. The contact members l! and i3 are each biased by suitable means, not shown, so as to ride on the low portion of their associated cams to open the respective contacts 9--l0, [Tl-52 and lS-ill when the shaft t is rotated to bring the lowered portion cf the cams into engagement with the respective contact members. The high or contact making portions of the cams 5, 6 and i are so proportioned that starting from the position shown, cani li closes contact Q i for 120a rotation of the shaft 8 in a counterclockwise drection, cam G closes contact lP--iZ for the next 69 rotation of the shaft, cam 'i closes contact I3-I4 for the next 120 rotation of the shaft, and cam again closes contact ll-l for the last rotation of the shaft El in the counterclockwise direction. It follows that with motor M rotating sii-aft at a uniform speed, the above cycle of operation for the contacts -i, ii-IZ and I3-Ill will be periodically repeated to provide a definite period of during which each contact is closed. Contact 'Q -i8 of signal timer ST is included iL -n operating circuit extending from the BX t iinal of a suitable source of current, such as the secondary winding l of a transformer, the winding lt of which is connected with a generator not shown, through contact .ll- IIL then through the lamps G of slgnals F and H and the lamps R of signals D and E in parallel, and thence to the other terminal CX of winding I5 of the transformer. In order to simplify the drawing, the lamps G, Y and R 5 for the signals D, E, F and H, when shown in circuit with the control contacts, are shown for convenience grouped together and not at their actual location on the respective corners of the intersection of routes A, B and C, it being understood that actually each lamp for the right-of- Way signals is located at the intersection as indicated in the drawing by the signals D, E, F and H there positioned.

The directional arrows LP for turnout signals LTI and LT2 are normally operated in parallel with the lamps G of signals F and H and lamps R of signals D and E, the circuit for the arrows LP being the same as the above traced circuit through contact 9-I0 of signal timer ST, and then passing through front contact I1 of a relay LTR to be referred to later, and the lamps of arrows LP of signals LTI and LT2, in parallel, to terminal CX. The lamps of the directional arrows LP and LS are shown for convenience grouped near the lamps of signals D, E, F and H, it being understood that in actual practice such lamps will be located at the intersection of routes A, B and C as indicated in the drawing.

Contact I |-I2 of signal timer ST is interposed in an operating circuit for lamps Y of signals D, E, F and H, the circuit passing from the BX terminal through contact II-IZ of signal timer ST, and the lamps Y of signals D, E, F and H in parallel, to terminal CX.

Contact i3--I4 of signal timer ST is interposed in an operating circuit extending from terminal BX through contact I3-I4, the lamps R of signals F and H and the lamps G of signals D and E in multiple, and then to terminal CX. The directional arrows LS of signals LTI and LT2 are normally operated in parallel with the lamps R of signals F and H and the lamps G of signals D and E, the circuit for the arrows LS being the same as the just traced circuit for lamps R of signals F and H and lamps G of signals D and E, through contact I3-I4, and then passing through front contact I8 of relay LTR and the lamps of arrows LS of signals LTI and LTZ in parallel, to terminal CX.

From the foregoing, it is apparent that when motor M of signal timer ST is energized in a manner to be described presently, during the first operation of the signal timer the lamps R. of signals D and E are illuminated to indicate stop to traffic on street A, the lamps G of signals F and H are illuminated to indicate proceed to traflic on street B and track C, and the directional arrows LP of signals LTI and LT2 are illuminated to indicate that trafc on street B is permitted to turn left from street B onto street A and across track C. During the next 60 operation of the signal timer, the yellow lamps Y of signals D, E, F and H are illuminated to indicate to all traic that the right-of-way indication is about to be changed, and the directional arrows LP and LS of signals LTE and LT2 are dark. During the next 120 operation of the signal timer, the lamps G of signals D and E are illuminated to display proceed to trafc on street A, the lamps R of signals F and H are illuminated to display stop traffic on street B and track C, and the directional arrows LS are illuminated to indicate that trac on street B is prevented from turning off street B on to street A and across u tracks C. Then, durlngthe last `operation of the signal timer, the yellow lampsY ofsignals D, E, F and H are illuminated to indicate that the right-of-way indication is `about to be changed, and the directional arrows LS and LP of signals LTI and LTZ are lldark.' This operating cycle forthe control of theright-of-waycsignals yD, E", F and H, and of the turnout signals LTI and LT2, will be periodically repeated as long as is the rst to be deenergized. is released, the relay completes a simple circuit motor M of the signal timer ST is' energized.

In order to establish preference for one class of trac over the other class of trailic at rthe intersection of routes A, B and C,the track rails I and Ia of track C are divided by means of the v usual insulated track joints. 2 into track sections M-M and N-O, which extend in opposite directions from' the intersecting traic route A. The track sections M-N and N-O are provided with track circuits here shown comprising in each lnstance a suitable source of current, such as track battery 3, connected across the track rails at one end of the section, and one winding Wi or W2, respectively, of an interlocking relay vXR connected across the'track'rails at the'other end. 'I'he windingWI and W2 of relay XR are responsive each to the presence of trains upon the associated track "section, but are arranged so that only the first winding of the two windings to be successively deenergized is permitted to open or close its control conta-cts, the other winding being held at an interlocked position in which the winding cannot open or close its control contacts, when this other winding is deenergized during the interval that the rst winding is still deenergized. The relay XR may take any one of y many well-known forms, one type oil which is `shown and' described in United States Letters Patent No. 1,799,629, grant-ed to-W. K. Lockhart and T. J. OMeara on'April '7, 1931. l

The reference character MR designates a control relay'governed jointly lov4 relay XR andk by signal timer ST, for controlling signal timer ST to retain the railway-highway signals F and H at a cleared condition when trains approach the intersection of the track C and the street A from either direction. A circuit yfor relay MR maybe traced from terminal BX through contact S-I Iof signal timer ST, back contact I9 or 2U of winding WI or W2, respectively, and the winding of relay MR to terminal CX. Alcontrol circuit for motor M of signal timer-ST passes from terminal BX throughback contact 2I in multiple with back` contact 22 ofl relay MR, and the lmotor M to terminal CX. From the 4foregoing it is apparent that when relay MR is released motor M is energized and operates signal timer ST to` thereby` effect cyclic operation of signals D, E, F, H, LTI and LTE, but that, relay MR is picked up when contact 1 -I0 of timer ST is closed and winding WI or, W2 of relay XR is-relcased by a train ontrackC'approaching street A, to-terminatethe operation of v'timer ST and to retain contact 9 4!! of that timer closed. Contact S-IIJ of timer ST closed completes vthe circuits whereby signals F and H indicate proceed and signals D and E* indicate stop;l

The reference character LTR designates a control relayy governed by winding WI or W2 of relay XR, for at times conditioningjturnoutsignals LT! and LT2 for operation by signal timer ST in step or register with the associated railway-highway signals F and H. Relay LTR is normally energized over a circuit passing from .terminal BX through front Contact 23 and front contact 2t of winding WIl and W2, respectively, of relay XR,

, I s and the winding of' relay LTR to terminal CX. The front contacts 23 and 24 of relay XR are characterized, as pointed out hereinbefore, by the fact that each contact is'opened only when its associated winding of the interlocking relay is i'.

the rst winding of the two to be successively deenergized, so that relay LTR will be released only when its circuit is opened by the releasing of winding WI or W2 according as such winding When relay LTR apparent from the oregoing that when relay LTR is released, signals LTI and LTE are removed from control by the signal timer means ST, and are controlled to their distinctive indications over back contact 25 of control relay LTR.

In describing the operation of the apparatus embodying my invention, I shall first assume that no train on track C is approaching the intersecting street A within the limits of the track sections M-N and N-Q With sections M-N and N-O unoccupied, windings WI and W2 of relay XR are pick-ed up, holding the circuit for relay MR opened so that relay MR is released, and the circuit for relay LTR closed so that relay LTR is picked up. As was pointed out hereinbefore, with relayv MR released the circuit for motor M isr completed so that the signal timer ST operates to cyclically control theoperation of the right-of-way signals D, E, F and H, at a uniform rate and in a manner such that the signals are alternately cleared for each street. And with relay LTR picked up, signals LTI and LTZ are conditioned for operation by signal timer ST in register with the operation of the associated signals F and H. i

I shall now assume that an eastbound train, operating on `track C, enters section M-N on its wayl toward the intersecting street A. When this happens, winding WI lis released to open its front contact 23, thereby lopening the circuit for relay LTR whereupon that relay'releases to remove the signal timer ST from control of the turnout signals LTI and LT2, and to control directional arrows LS to their illuminated condition. The display of the illuminated red arrows LS of signals LTI and LTZ nov/'operate vto prevent traffic operating on street B from turning onto street A and across track C., `Winding WI in releasing also closes its back contact I9 so that when signal timer ST is operated to close its contact .Q -Iii, the circuit previously traced for relayMR -is completed whereupon that relay picks up to open its backcontacts 2l and 22 and thereby deenergize motor M of timer ST. It is readily ap- Cal trafhc on street A is signaled to prevent traic movements across street B and track C. As pointed out hereinbefore, signals F and H may also be used to control railway traffic, and the display of the green G indication of signal I-I would indicate a proceed signal to the eastbound train, thereby informing the engineman of that train that tlie intersection is properly signaled .for train movements. t is readily apparent, thereforey that the highway crossing is signaled to permit non-interfering movements when a train approaches the intersection, but all highway trafiie movements interfering with the preferred movement o the railway traic are prevented.

When the train enters section N-O and winding W2 is deenergized, the interlocking feature of the relay X prevents front contact 24 from opening and back contact 25 from closing, so that when the train vacates section M-N and winding Wi picks up, the circuit for relay LTR is reestablished whereupon that relay picks up to condition signals LTi and LTZ for operation by signal timer ST, and relay MR is released to reestablish the circuit for motor M to restore the cyclic operation o the signal tiiner and of the right-of-vJa-y and turnout signals. Then, when the train vacates section N-O, winding W2 reenergizes to restore relay XR to its normal condition.

The operation of the apparatus for a westbound train approaching street A is substantially similar to the operation just described for an eastbound train, as can readily be understood from an inspection of the drawing, and further detailed description is deemed unnecessary.

From the foregoing description of the operation oi the apparatus embodying my invention, it is readily apparent that I have provided a signaling system for nori .ally cyclically controlling traffic of one class operating over interfering traic routes, but which at times establishes preference to a superior class of traffic operating over a trafiic route interfering with suoli other trafc routes. Furthermore, it is apparent that when the superior class of traffic is granted preference in movement, all movements of the one class of traic which might interfere with the movements of the superior class are prevented.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described Vmy invention, what l claim is:

1. In combination, a stretch of railway track intersects by a rst tronic route, a second traffic route in said first tiaiiic .rout-e, railwayhighway s ing traffic movements on said second trafc route across said first traiiic route, turnout signals for governing traffic morcon said second traffic route turning onto said first traffic route, liighiny signals for governing tr across said second t track, a g devi e7 means for normally energizing said timing device, means controlled by said timing device when energized foi' clearing said high nais alternately with said rail.- way-lighway anais, a control relav. means for normally ener izing said control relay, means controlled by said control relay when energized lor conditioning turnout signals for cyclic operation by said timing device in register with the operation of said railway-highway signals, means governed by said control relay when deenergized for controlling said turnout signals to the danger condition, and means governed by a train on said railway track effective when said train approaching said rst traffic route from either direction for deenergizing said control relay and for deenergizing said timing device for retaining said railway-highway signals in the cleared condition and effective when said train is receding from said tra-flic route for reenergizing said control relay and said timing device.

2. In combination, a stretch of railway track intersectecl by a first traffic route, a second traffic route intersecting said rst traffic route, railwayhighway signals for governing traiiic movements on said second traffic route across said first tra-ffic route, turnout signals for governing traiic movements on said second traffic route turning onto said rst traffic route, highway signals for governing traic movements on said first traic route across said second tramo route and said railway track, a timing device, means for normally energizing said timing device, a control relay, means'for normally energizing said control relay, means governed by said control relay when energized for normally conditioning said turnout signals for control by said timing device, means governed by said control relay when deenergized for controlling said turnout signals to the danger condition, means governed by said timing device when energized for clearing said highway signals alternately with said railwayhighway and turn out signals, means governed by a train on said railway track effective when said train is approaching saidl first traffic route from either direction for deenergizing said timing device for retaining said railway-highway signals at the cleared condition and for deenergizing said control relay, and directional means governed by said train when receding from said traiic route for causing said timing means to become energized and for causing said control relay to become energized.

3. In combination, a stretch of railway track intersected by a first traffic route, a second traflic route intersecting said first traffic route, railwayhighway signals for governing traflic movements on said second trahie route across said rst traic route, turnout signals for goverrnng traffic movements on said second traino route turning onto said first traffic route, highway signals for goverining traiic movements on said iirst traffic route across said second trac route and said railway track, a timing device, means for normally energizing said timing device, a control relay, means for normally energizing said control relay, means governed by said control relay when energized for conditioning said turnout signals for control by said timing device, means governed by said timing device when energized for clearing said highway signals alternately with said railway-highway and turnout signals, means governed by a train on said railway track effective when said train is approaching said first traffic route from either direction for deenergizing said timing device for retaining said railwayhighway signals at the cleared condition and for deenergizing said control relay, means governed by said control relay when deenergized for controlling said turnout signals to the danger condition, and directional means governed by said train receding from said first trame route for causing said timing device and said control relay to become reenergized.

4. In combination, two traffic routes intersecting at grad-e and each having means for displaying right-of-way signall indications, astretch of railway track adjacent one of `said traiiic routes and intersecting the other of said trame routes at grade, turnout signal means for controlling traffic movements on said one route turning onto said other route and across said railway track, signal timer means for normally cyclically displaying said right-o-way indications successively to said two traffic routes, a control relay, means governed by said control relay when energized, for. conditioning said turnout signals for operation by said signal timer means in step with the right-ofway indications displayed to said one traflic route, means governed by a train on said railway track eiective when said train approaches said other traffic route from either direction for controlling said signal timer means to display right-of-way signal indictions to said one traffic route and for deenergizing said signal control relay, and means .governed by said control relay when deenergized to control said turnout signals to the danger condition.

f 5. In combination, -two traiiic routes intersecting at grade and eachhaving means for display- -ing right-of-way signal indications, a stretch of railway track adjacent oneoi said traiic routes and intersecting the other of 'said traffic routes at grade, turnout signal means for controlling traic movements'on said. one trafc route turning onto said other traffic route and across said railway track, signal timer means for normally cyclically displaying said right-of-way indications `successively to said two traflic routes, signal control means for normally conditioning said turnout signal means for control by said signal timer means in register with the control of the rightof-way indication-for said one tramo route, other means governed by said signal control means for operating said turnout signals to the danger condition, and means governedV by a train on said railway track eiective when said train is approaching said other traine route for rendering said signal timer means ineffective to cyclically display said indications and to give the right-of- -way indication to said one traffic route and for rendering said signal control means ineffective to condition said turnout signals for control by said signal lcontrol means and to control said signal control means to operate said turnout signals to the danger condition.

6. The combination in a signaling system having means for cyclically operating right-of-Way signals to display right-of-way indications successively to each of two intersecting trac routes, one route of which contains a stretch of railway track intersected at grade by the other trafc route, of auxiliary signals for controlling traffic in one of said two traic routes, means normally effective for operating said auxiliary signals in step or register with the right-of-way signals of the associated one of said two traic routes, means controlled by a train on said stretch approaching theintersecting traffic route for terminating the cyclic operation of said right-ofway signals to cause right-of-way indications to bedisplayed to the one of said two traffic routes containing the stretch of railway track, and other means controlled by said train approaching the intersecting trac route for controlling said auxiliary signals to display indications out of register with said associated right-of-way signals.

RONALD A. MCCANN. 

